arXiv subjects

Xingpeng Li

Publications and source records attributed to Xingpeng Li.

102 records · Page 6Linked to original sources

arXiv2020

Benefits and Cyber-Vulnerability of Demand Response System in Real-Time Grid Operations

With improvement in smart grids through two-way communication, demand response (DR) has gained significant attention due to the inherent flexibility provided by shifting non-critical loads from peak periods to off-peak periods, which can greatly improve grid reliability and reduce cost of energy. Operators utilize DR to enhance operational flexibility and alleviate network congestion. However, the intelligent two-way communication is susceptible to cyber-attacks. This paper studies the benefits of DR in security-constrained economic dispatch (SCED) and then the vulnerability of the system to line overloads when cyber-attack targets DR signals. This paper proposes a false demand response signal and load measurement injection (FSMI) cyber-attack model that sends erroneous DR signals while hacking measurements to make the attack undetectable. Simulation results on the IEEE 24-bus system (i) demonstrate the cost-saving benefits of demand response, and (ii) show significant line overloads when the demand response signals are altered under an FSMI attack.

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arXiv2020

Reducing Congestion-Induced Renewable Curtailment with Corrective Network Reconfiguration in Day-Ahead Scheduling

Renewable energy sources (RES) has gained a lot of interest recently. The limited transmission capacity serving RES often leads to network congestion since they are located in remote favorable locations. As a result, when poorly scheduled, the intermittent nature of RES may result in high curtailments of the free resource. Currently, grid operators utilize a static network when performing day-ahead scheduling and ignore transmission flexibility. This paper explores the possibility of utilizing network reconfiguration as a corrective action to reduce the transmission congestion and thereby the reduction of RES curtailments in day-ahead scheduling. To facilitate the RES integration in the grid, a stochastic N-1 security-constrained unit-commitment with corrective network reconfiguration (SSCUC-CNR) is modelled. SSCUC-CNR model is studied on a modified IEEE 24-bus system with RES. The simulation results demonstrate that CNR not only leads to a lower cost solution by reducing network congestion but also facilitates RES integration by reducing congestion-induced curtailments in high penetration cases. Emission studies demonstrate that more green generators are committed resulting in reduced carbon emissions when CNR is implemented.

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arXiv2020

Security Constrained Unit Commitment with Corrective Transmission Switching

Traditionally, power system operations use a static network to deliver power and meet demand optimally. Network topology reconfiguration through transmission switching (TS) has gained significant interest recently to reduce the operational cost of power system operations. However, implementation of TS also causes large disturbance in the network and as a result the use of corrective transmission switching (CTS) in response to power system contingencies is currently being researched extensively. This paper emphasizes the importance of CTS to accomplish flexible transmission in N-1 security-constrained unit commitment (SCUC) model. An N-1 SCUC mathematical model implementing a dynamic network in the post-contingency scenario is proposed as opposed to current industry practices of static network in short-term operations. The proposed model is tested and validated on the IEEE 24-bus system. The proposed model results in cost-effective implementation and leads to overall reduced cost, and congestion reduction in the post-contingency scenario.

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arXiv2019

Sensitivity Factors based Transmission Network Topology Control for Violation Relief

Transmission networks consist of thousands of branches for large-scale real power systems. They are built with a high degree of redundancy for reliability concern. Thus, it is very likely that there exist various network topologies that can deliver continuous power supply to consumers. The optimal transmission network topology could be very different for different system conditions. Transmission network topology control (TNTC) can provide the operator with an additional option to manage network congestion, reduce losses, relieve violation, and achieve cost saving. This paper examines the benefits of TNTC in reducing post-contingency overloads that are identified by real-time contingency analysis (RTCA). The procedure of RTCA with TNTC is presented and two algorithms are proposed to determine the candidate switching solutions. Both algorithms use available system data: sensitivity factors or shifting factors. The proposed two TNTC approaches are based on the transmission switching distribution factor (TSDF) and flow transfer distribution factor (FTDF) respectively. FTDF based TNTC approach is an enhanced version of TSDF based TNTC approach by considering network flow distribution. Numerical simulations demonstrate that both methods can effectively relieve flow violations and FTDF outperforms TSDF.

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arXiv2019

Enhancing Power System Cyber-Security with Systematic Two-Stage Detection Strategy

State estimation estimates the system condition in real-time and provides a base case for other energy management system (EMS) applications including real-time contingency analysis and security-constrained economic dispatch. Recent work in the literature shows malicious cyber-attack can inject false measurements that bypass traditional bad data detection in state estimation and cause actual overloads. Thus, it is very important to detect such cyber-attack. In this paper, multiple metrics are proposed to monitor abnormal load deviations and suspicious branch flow changes. A systematic two-stage approach is proposed to detect false data injection (FDI) cyber-attack. The first stage determines whether the system is under attack while the second stage identifies the target branch. Numerical simulations verify that FDI can cause severe system violations and demonstrate the effectiveness of the proposed two-stage FDI detection (FDID) method. It is concluded that the proposed FDID approach can efficiently detect FDI cyber-attack and identify the target branch, which will substantially improve operators situation awareness in real-time.

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arXiv2019

Stochastic Optimal Power Flow with Network Reconfiguration: Congestion Management and Facilitating Grid Integration of Renewables

There has been a significant growth of variable renewable generation in the power grid today. However, the industry still uses deterministic optimization to model and solve the optimal power flow (OPF) problem for real-time generation dispatch that ignores the uncertainty associated with intermittent renewable power. Thus, it is necessary to study stochastic OPF (SOPF) that can better handle uncertainty since SOPF is able to consider the probabilistic forecasting information of intermittent renewables. Transmission network congestion is one of the main reasons for renewable energy curtailment. Prior efforts in the literature show that utilizing transmission network reconfiguration can relieve congestion and resolve congestion-induced issues. This paper enhances SOPF by incorporating network reconfiguration into the dispatch model. Numerical simulations show that renewable curtailment can be avoided with the proposed network reconfiguration scheme that relieves transmission congestion in post-contingency situations. It is also shown that network reconfiguration can substantially reduce congestion cost, especially the contingency-case congestion cost.

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arXiv2019

Transmission Expansion Planning with Seasonal Network Optimization

Transmission expansion planning (TEP) is critical for the power grid to meet fast growing demand in the future. Traditional TEP model does not utilize the flexibility in the transmission network that is considered as static assets. However, as the load profile may have different seasonal patterns, the optimal network configuration could be very different for different seasons in the planning horizon. Therefore, this paper proposes to incorporate seasonal network optimization (SNO) into the traditional TEP model. SNO dynamically optimizes the network for each season of each planning epoch. Two TEP-SNO models are proposed to investigate the benefits of optimizing the status of (i) existing branches, and (ii) existing and new branches, respectively. Numerical simulations demonstrate the effectiveness of the proposed TEP-SNO models. It is shown that SNO can improve system operational efficiency, defer investment of new transmission elements, and reduce the total cost.

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arXiv2019

Enhanced Energy Management System with Corrective Transmission Switching Strategy. Part I: Methodology

The flexibility in transmission networks is not fully utilized and reflected in existing energy management systems (EMSs). Corrective transmission switching (CTS) is proposed in this two-part paper to enable EMS to take advantage of the flexibility in transmission systems in a practical way. This paper proposes two EMS procedures: 1) Procedure-A connects real-time security-constrained economic dispatch (RT SCED) with real-time contingency analysis (RTCA), which is consistent with industrial practice; 2) Procedure-B, an enhanced version of Procedure-A, includes CTS in EMS with the proposed concept of branch pseudo limit used in RT SCED. Part-I of this paper presents the methodology while Part-II includes detailed results analysis. It is demonstrated that Procedure-A can effectively eliminate the potential post-contingency overloads identified by RTCA and Procedure-B can achieve significant congestion cost reduction with consideration of CTS in RT SCED. Numerical simulations also illustrate that integrating CTS into RT SCED would improve social welfare.

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arXiv2019

Enhanced Energy Management System with Corrective Transmission Switching Strategy. Part II: Results and Discussion

This paper presents a novel procedure for energy management system (EMS) that can utilize the flexibility in transmission network in a practical way. With the proposed enhanced EMS procedure, the reliability benefits that are provided by corrective transmission switching (CTS) in real-time contingency analysis (RTCA) can be translated into significant cost savings in real-time security-constrained economic dispatch (RT SCED). Simulation results show the congestion cost with consideration of CTS is largely reduced as CTS can relieve potential post-contingency network violations. The effects of integrating CTS in existing EMS procedure on markets are also analyzed. In conclusion, this two-part paper shows that CTS can achieve substantial reliability benefits, as well as significant cost savings.

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arXiv2018

Data Driven Linearized AC Power Flow Model with Regression Analysis

Full AC power flow model is an accurate mathematical model for representing the physical power systems. In practice, however, the utilization of this model is limited due to the computational complexity associated with its nonlinear and nonconvexity characteristics. An alternative linearized DC power flow model is widely used in the power system operation and planning tools. However, when reactive power and voltage magnitude are of concern, DC power flow model will be useless. Therefore, a linearized AC (LAC) power flow model is needed to address this issue. This paper first introduces a regular LAC model. Subsequently, with the advance in regression analysis technique, a data driven linearized AC (DLAC) model is proposed to improve the regular LAC model. Numerical simulations conducted on the Tennessee Valley Authority (TVA) system demonstrate the performance and effectiveness of the proposed DLAC model.

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arXiv2016

Real-Time Contingency Analysis with Corrective Transmission Switching - Part I: Methodology

Transmission switching (TS) has gained significant attention recently. However, barriers still remain and must be overcome before the technology can be adopted by the industry. The state of the art challenges include AC feasibility and performance, computational complexity, the ability to handle large-scale real power systems, and dynamic stability. This two-part paper investigates these challenges by developing an AC TS-based real-time contingency analysis (RTCA) tool that can handle large-scale systems within a reasonable time. The tool proposes multiple corrective switching actions, after detection of a contingency with potential violations. To reduce the computational complexity, three heuristic algorithms are proposed to generate a small set of candidates for switching. Parallel computing is implemented to further speed up the solution time. Furthermore, stability analysis is performed to check for dynamic stability of proposed TS solutions. Part I of the paper presents a comprehensive literature review and the methodology. The promising results, tested on the Tennessee Valley Authority (TVA) system and actual energy management system (EMS) snapshots from Pennsylvania New Jersey Maryland (PJM) and the Electric Reliability Council of Texas (ERCOT), are presented in Part II. It is concluded that RTCA with corrective TS significantly reduces potential post-contingency violations and is ripe for industry adoption.

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arXiv2016

Real-Time Contingency Analysis with Corrective Transmission Switching - Part II: Results and Discussion

This paper presents the performance of an AC transmission switching (TS) based real-time contingency analysis (RTCA) tool that is introduced in Part I of this paper. The approach quickly proposes high quality corrective switching actions for relief of potential post-contingency network violations. The approach is confirmed by testing it on actual EMS snapshots of two large-scale systems, the Electric Reliability Council of Texas (ERCOT) and the Pennsylvania New Jersey Maryland (PJM) Interconnection; the approach is also tested on data provided by the Tennessee Valley Authority (TVA). The results show that the tool effectively reduces post-contingency violations. Fast heuristics are used along with parallel computing to reduce the computational difficulty of the problem. The tool is able to handle the PJM system in about five minutes with a standard desktop computer. Time-domain simulations are performed to check system stability with corrective transmission switching (CTS). In conclusion, the paper shows that corrective switching is ripe for industry adoption. CTS can provide significant reliability benefits that can be translated into significant cost savings.

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